TY  - JOUR
A1  - Zhuang, Y.
A1  - Schelling, Christoph
A1  - Stangl, Jochen
A1  - Penn, C.
A1  - Senz, S.
A1  - Schäffler, Friedrich
A1  - Roche, T.
A1  - Daniel, A.
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Bauer, Günther
T1  - Structural and optical properties of Si/Si{1-x}Ge{x} wires
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Zhuang, Y.
A1  - Pietsch, Ullrich
A1  - Stangl, Jochen
A1  - Holý, Vaclav
A1  - Darowski, Nora
A1  - Grenzer, Jörg
A1  - Zerlauth, S.
A1  - Schäffler, F.
A1  - Bauer, Günther
T1  - In-plane strain and shape analysis of Si/SiGe nanostructures by grazing incidence diffraction
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Zhuang, Y.
A1  - Holý, Václav
A1  - Stangl, Jochen
A1  - Darhuber, A.
A1  - Mikulik, P.
A1  - Zerlauth, S.
A1  - Schäffler, F.
A1  - Bauer, Günther
A1  - Darowski, Nora
A1  - Lübbert, Daniel
A1  - Pietsch, Ullrich
T1  - Strain relaxation in periodic arrays of Si/SiGe quantum wires determined by coplanar high-resolution x-ray diffrcation and grazing-incidence diffraction
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Zen, Achmad
A1  - Saphiannikova, Marina
A1  - Neher, Dieter
A1  - Grenzer, Jörg
A1  - Grigorian, Souren A.
A1  - Pietsch, Ullrich
A1  - Asawapirom, Udom
A1  - Janietz, Silvia
A1  - Scherf, Ullrich
A1  - Lieberwirth, Ingo
A1  - Wegner, Gerhard
T1  - Effect of molecular weight on the structure and crystallinity of poly(3-hexylthiophene)
N2  - Recently, two different groups have reported independently that the mobility of field-effect transistors made from regioregular poly(3-hexylthiophene) (P3HT) increases strongly with molecular weight. Two different models were presented: one proposing carrier trapping at grain boundaries and the second putting emphasis on the conformation and packing of the polymer chains in the thin layers for different molecular weights. Here, we present the results of detailed investigations of powders and thin films of deuterated P3HT fractions with different molecular weight. For powder samples, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) were used to investigate the structure and crystallization behavior of the polymers. The GPC investigations show that all weight fractions possess a rather broad molecular weight distribution. DSC measurements reveal a strong decrease of the crystallization temperature and, most important, a significant decrease of the degree of crystallinity with decreasing molecular weight. To study the structure of thin layers in lateral and vertical directions, both transmission electron microscopy (TEM) and X-ray grazing incidence diffraction (GID) were utilized. These methods show that thin layers of the low molecular weight fraction consist of well-defined crystalline domains embedded in a disordered matrix. We propose that the transport properties of layers prepared from fractions of poly(3-hexylthiophene) with different molecular weight are largely determined by the crystallinity of the samples and not by the perfection of the packing of the chains in the individual crystallites
Y1  - 2006
UR  - http://pubs.acs.org/doi/full/10.1021/ma0521349
U6  - https://doi.org/10.1021/Ma0521349
ER  - 
TY  - JOUR
A1  - Zeimer, Ute
A1  - Pietsch, Ullrich
A1  - Grenzer, Joerg
A1  - Fricke, J.
A1  - Knauer, A.
A1  - Weyers, Markus
T1  - Optimised two layer overgrowth of a lateral strain-modulated nanostructure
N2  - Recently it has been shown that lateral carrier confinement in an InGaAs quantum well (QW) embedded in GaAs can be achieved by using a laterally patterned InGaP stressor layer on top of the heterostructure. To exploit this effect in a device the structure has to be planarized by a second epitaxial step. It has been shown that the lateral strain modulation almost vanishes after overgrowth with GaAs, whereas overgrowth with a single ternary layer of opposite strain compared to the stressor layer suffers from strain induced decomposition. Here we show that the lateral carrier confinement of the initially free standing nanostructure can almost be maintained using a two step process for overgrowth, where a strained thin ternary layer is grown first followed by GaAs up to complete planarization of the patterned structure. Thickness and composition of the ternary layer are adjusted on the basis of finite element calculations of the strain distribution (FEM). The strain field achieved after overgrowth is probed by X-ray grazing- incidence diffraction (GID). (c) 2005 Elsevier B.V. All rights reserved
Y1  - 2005
SN  - 0925-8388
ER  - 
TY  - JOUR
A1  - Zeimer, Ute
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Bugge, F.
A1  - Smirnitzki, V.
A1  - Weyers, Markus
T1  - Investigation of strain-modulated InGaAs-nanostructures by grazing-incidence x-ray diffraction and photoluminescence
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Zeimer, Ute
A1  - Bugge, F.
A1  - Gramlich, S.
A1  - Smirnitzki, V.
A1  - Weyers, Markus
A1  - Tränkle, G.
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Cassabois, G.
A1  - Emiliani, V.
A1  - Linau, Christoph
T1  - Evidence of strain-induced lateral carrier confinement in InGaAs-quantum wells by low-temperature near-field spectroscopy
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Zeimer, Ute
A1  - Bugge, F.
A1  - Gramlich, S.
A1  - Smirnitzki, V.
A1  - Weyers, Markus
A1  - Tränkle, G.
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Cassabois, G.
A1  - Emiliani, V.
A1  - Lienau, C.
T1  - Evidence for strain-induced lateral carrier confinement in InGaAs quantum wells by low-temperature near-field spectroscopy
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Zeimer, Ute
A1  - Baumbach, Tilo
A1  - Grenzer, Jörg
A1  - Lübbert, Daniel
A1  - Mazuelas, A.
A1  - Pietsch, Ullrich
A1  - Erbert, G.
T1  - In-situ characterization of strain distribution in broad-area high-power lasers under operation by high- resolution x-ray diffrcation and topography using synchrotron radiation
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Veldkamp, Markus
A1  - Erko, Alexei
A1  - Gudat, Wolfgang
A1  - Abrosimov, Nikolai V.
A1  - Alex, Volker
A1  - Khasanov, Salavat
A1  - Neissendorfer, Frank
A1  - Pietsch, Ullrich
A1  - Shekhtman, Veniamin
T1  - Si(1-x)Ge(x) laterally graded crystals as monochromators for X-Ray absorption spectroscopy studies
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Ulyanenkov, A.
A1  - Klemradt, U.
A1  - Pietsch, Ullrich
T1  - Investigation of strain relaxation in GaInAs/GaAs superlattices by x-ray diffuse scattering
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Ulyanenkov, A.
A1  - Darowski, Nora
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Wang, K. H.
A1  - Forchel, Alfred
T1  - Evaluation of strain distribution in freestanding and bruied lateral nanostructures
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Ulyanenkov, A.
A1  - Baumbach, Tilo
A1  - Darowski, Nora
A1  - Pietsch, Ullrich
A1  - Wang, K. H.
A1  - Forchel, Alfred
A1  - Wiebach, T.
T1  - Investigation of the in-plane strain distribution in free-standing GaAs/InGaAs/GaAs single quantum well surface nanostructures on GaAs[001]
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Tsirelson, Vladimir G.
A1  - Avilov, Anatoly S.
A1  - Lepeshov, G. G.
A1  - Kuligin, A. K.
A1  - Stahn, Jochen
A1  - Pietsch, Ullrich
A1  - Spence, J. C. H.
T1  - Quantitative Analysis of the Inner-Crystal Electrostatic Potential of several Rock-Salt-Structure Crystals Using Accurate Electron-Diffraction Data
Y1  - 2001
SN  - 1089-5647
ER  - 
TY  - JOUR
A1  - Tsirelson, Vladimir G.
A1  - Abramov, Yury Fedorovich
A1  - Zavodnik, Valerie E.
A1  - Stash, Adam I.
A1  - Belokoneva, Elena L.
A1  - Stahn, Jochen
A1  - Pietsch, Ullrich
A1  - Feil, Dirk
T1  - Critical pionts in a crystal an procrystal
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Thünemann, Andreas F.
A1  - Kubowicz, Stephan
A1  - Pietsch, Ullrich
T1  - Ultra-thin solid polyelectrolyte-surfactant complex films : structure and wetting
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Talalaev, V
A1  - Tomm, JW
A1  - Elsaesser, T
A1  - Zeimer, Ute
A1  - Fricke, J
A1  - Knauer, A
A1  - Kissel, H
A1  - Weyers, Markus
A1  - Tarasov, GG
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
T1  - Carrier dynamics in laterally strain-modulated InGaAs quantum wells
N2  - We investigate the transient recombination and transfer properties of nonequilibrium carriers in an In0.16Ga0.84As/GaAs quantum well (QW) with an additional lateral confinement implemented by a patterned stressor layer. The structure thus contains QW- and quantum-wire-like areas. At low excitation densities, photoluminescence (PL) transients from both areas are well described by a rate equation model for a three-level system with a saturable interlevel carrier transfer representing the lateral drift of carriers from the QW regions into the wires. Small-signal carrier lifetimes for QW, wires, and transfer time from QW to wire are 180, 190, and 28 ps, respectively. For high excitation densities the time constants of the observed transients increase, in agreement with the model. In addition, QW and wire PL lines merge indicating a smoothening of the potential difference, i.e., the effective carrier confinement caused by the stressor structure becomes weaker with increasing excitation. (c) 2005 American Institute of Physics
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Stömmer, Ralph
A1  - Zeimer, Ute
A1  - Pietsch, Ullrich
T1  - Diffuse Röntgenstreuung an LB-Filmen
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Stömmer, Ralph
A1  - Martin, C. R.
A1  - Geue, Thomas
A1  - Göbel, H.
A1  - Hub, W.
A1  - Pietsch, Ullrich
T1  - Comparative studies of fractal parameters of Si(100) surfaces measured by X-ray scattering and atomic force microscopy
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Stömmer, Ralph
A1  - Göbel, H.
A1  - Hub, W.
A1  - Pietsch, Ullrich
T1  - X-ray scattering from silicon surfaces
Y1  - 1998
ER  -